Field of the Invention
This invention relates to a wire bundle and a communication cable having one or more wire bundles.
Description of Related Art
Communication cables are conventionally used in various networks (e.g., a telephone line, a railway signal protection device, a local area network (LAN), and a vehicle-mounted network (CAN)). Such a communication cable has a wire bundle(s) (a stranded wire(s)) formed by twisting insulated wires, which each include a conductor core covered with an insulator.
For example, one of conventional communication cables (hereinafter referred to as a “conventional cable”) is formed by twisting a plurality of wire bundles (in particular, quad-stranded wires, which each is formed by twisting four insulated wires). Each of the wire bundles (quad-stranded wires) of this conventional cable has an annular shape (doughnut shape), which has a circular outer perimeter and a circular inner perimeter in a cross section perpendicular to an axis line of the wire bundle. Furthermore, each of the insulated wires of this wire bundle has a wedge-shaped protrusion and a recess corresponding to its protrusion, and is configured to mutually bond the adjacent insulated wires by engagement between the protrusion and the recess. The conventional cable is designed to eliminate a deformation of the quad shape (i.e., a relative displacement of the conductor cores) by this engagement to enhance the crosstalk attenuation characteristics, and is also designed to use an air layer of a region (hollow portion of the doughnut shape) surrounded by the inner perimeter of the wire bundle to reduce the electrostatic capacitance between the conductor cores to enhance the attenuation characteristics of a transmission signal.
As for details of the conventional example, refer to JP 2014-7018 A.